Similarities asks how two words are alike
In the WAIS Similarities subtest, the person hears two words and explains in their own words how the two are alike. The aim is not to describe only one of the words or name an event involving both. The answer must bring both words together under a shared higher-order concept.
In the Japanese WAIS-IV, Similarities is a core subtest of the Verbal Comprehension Index, or VCI, alongside Vocabulary and Information. Knowing the meanings of the words is only one part of the task. The score also reflects the ability to compare two concepts, select their essential common feature, and express it as a concise answer.
In the 2024 US WAIS-5, Similarities is a primary VCI subtest and is also used to calculate FSIQ. The edition named on the report determines the norms, scoring, and wider subtest structure.
Moving from a concrete similarity to an abstract common concept
Two things can share their appearance, the setting in which they are used, their purpose, or a broader category. Similarities looks for the concept that best captures the central meaning of both, rather than a feature they happen to share.
As an example that is not a test item, consider a map app and a public-transport journey planner. Saying that both are used on a smartphone identifies a surface similarity. Describing both as sources of information used to plan a route captures their central function in one concept.
The task therefore requires the person to retrieve the meanings of two words, compare their attributes and relationships, and express the common feature concisely. This is a form of verbal abstract reasoning in which the quality of the concept matters more than using unusually abstract vocabulary or giving a long explanation.
What higher and lower Similarities scores can show
A higher score indicates strength in identifying an essential common feature across individual examples and expressing it as a concise higher-order concept that another person can understand.
A lower score means that answers were more likely to remain at the level of individual features or situations rather than bringing both words together under a broader concept. A person may also recognize the common feature but find it difficult to phrase it briefly in a form that earns full credit.
Differences from the other verbal subtests can help identify where the demand arose:
- If Similarities is clearly lower than Vocabulary, comparing concepts and forming a common category was more demanding than retrieving the meanings of individual words.
- If Similarities and Vocabulary are both low, accurately retrieving and explaining word meanings may be contributing before the comparison is made.
- If Similarities is clearly lower than Information, reorganizing familiar meanings into a relationship was more demanding than retrieving acquired facts.
How to read WAIS results explains how to place a subtest difference within the complete score profile.
How Similarities differs from Vocabulary and Information
Similarities, Vocabulary, and Information all draw on acquired language and semantic knowledge. They differ in what the person must do with that knowledge.
| Subtest | Direct task | Main processing involved |
|---|---|---|
| Similarities | Explain what two words have in common | Comparing concepts, generating a shared relationship, and verbal abstract reasoning |
| Vocabulary | Explain the meaning of one word | Retrieving vocabulary, distinguishing precise meanings, and verbal expression |
| Information | Answer a question about a general fact | Retrieving acquired general knowledge |
Viewed together, the three Japanese WAIS-IV subtests show different ways of using verbal comprehension and acquired knowledge: what a person knows and how they reorganize known meanings to form a relationship.
Similarities and BrainTypeIQ Analogies share relational reasoning in different formats
BrainTypeIQ Analogies presents an example word pair, asks the person to identify its relationship, and then requires them to choose another pair with the same relationship. Like WAIS Similarities, it goes beyond the individual meanings of the words and asks how concepts are related.
| Task | What is presented | Required response |
|---|---|---|
| WAIS Similarities | One pair of words | Explain the concept shared by both words in a spoken response |
| BrainTypeIQ Analogies | An example word pair and several answer options | Choose the pair with the most similar relationship |
BrainTypeIQ uses a selection format that reduces the demand involved in composing an open-ended spoken answer and focuses on recognizing a relationship pattern and applying it to another pair. Its items, scoring, administration, and comparison norms are separate from WAIS. This format lets BrainTypeIQ measure relational reasoning as part of its five-domain cognitive profile.